The present invention relates to a stabilization apparatus for ship movements. The stabilizer apparatus includes adjustable stabilizers, drive devices by means of which the position of the stabilizers can be adjusted, a control device by means of which control signals corresponding to the required positions of the respective stabilizers can be produced and can be applied to the respective drive device, and a measurement device by means of which the rolling movements of a ship can be detected and measurement signals corresponding to the detected rolling movements can be produced and can be applied to the control device. The control device is designed so that a roll angle and a roll angle rate and/or a roll angle acceleration may be detected separately as measured variables, or may be determined separately from measured variables. A control signal which is produced in the control device in order to compensate for the rolling movement of the ship may be formed from a roll angle component and a roll angle rate component and/or a roll angle acceleration component. The elements of the roll angle components and the roll and rate component and/or the roll angle acceleration component may be preset in the control signal.
Eueopean Patent No. EP 0 591 366 describes a stabilization apparatus for ship movements, in which it is possible to compensate for the rolling movements of the ship. To this end, a control signal is produced which is characteristic of the rolling movement of the ship, leads to a specific movement of the stabilizers, and in this way counteracts the undesirable rolling movement of the ship.
Since the weather conditions and thus the requirements for the stabilization apparatus vary widely, the initially mentioned stabilization apparatus is unable to achieve the optimum stabilization result, which results from the physical characteristics, in all conditions.
Great Britain Patent No. GB 1 047 263 describes a stabilization apparatus for ship movements using which roll angle rates and accelerations may also be detected in order to improve the stabilization of the ship movements.
An object of the present invention is to provide a stabilization apparatus for ship movements which reduces pitching movements of the ship in an optimum manner both in a high sea and in any other weather conditions.
According to an example embodiment of the present invention, the stabilization device includes a measurement apparatus using which the pitching movements of the ship can be detected, measurement signals corresponding to the detected pitching movements can be produced and can be applied to the control device, which is designed such that a pitch angle and/or a pitch angle rate and/or a pitch angle acceleration can be detected separately as measured variables or can be determined separately from measured variables, such that a signal part of the control signal which is produced in the control device in order to compensate for the pitching movement of the ship can be formed from a pitch angle component and/or a pitch angle rate component and/or a pitch angle acceleration component, and such that the elements of the pitch angle component and/or of the pitch angle rate component and/or of the pitch angle acceleration component can be preset as required in that signal part of the control signal which is produced in order to compensate for the pitching movement. The priority circuit with smooth transitions with regard to the reduction in the pitching movements of the ship, also be used to compensate for the rolling movements.
A robust measurement device configuration with correct and reliable measurement signal production is ensured if the measurement devices which are used to detect the rolling and/or yawing and/or pitching movements of the ship are in the form of acceleration sensors.
In order to detect the rolling movements of the ship, it is advantageous for the measurement device for detecting the rolling movement to have three acceleration sensors, one of which is arranged in the region of the ship""s longitudinal axis, and the two others are arranged as far as possible to port and starboard, respectively.
Correspondingly, it is advantageous for detection of the pitching movement of the ship for the measurement device which is provided for this purpose to have three acceleration sensors, one of which is arranged in the region of the ship""s longitudinal axis and the two others are arranged offset as far as possible toward the bow and stern of the ship, respectively.
In order to detect the yawing movement of the ship as exactly as possible, it is advantageous for the measurement device to have three acceleration sensors, one of which is arranged in the region of the ship""s lateral axis and the two others are arranged offset as far as possible toward the bow and stern of the ship, respectively.
In order to reduce the complexity for the measurement devices of the stabilization apparatus according to the present invention as far as possible, it is expedient for one or more acceleration sensors to be designed and arranged such that they can be used to detect the rolling and/or yawing and/or pitching movement of the ship. One acceleration sensor can then be used to detect different ship movements, as a result of which it is possible to reduce the total number of acceleration sensors which are used to form the measurement devices.
The drive devices for moving the stabilizers may be components of a hydraulic system having a reservoir and a constant-pressure pump, in which case the actual filling level of the reservoir of the hydraulic system can be detected as a measured variable, and can be taken into account in the production of the control signal, in the control device of the stabilization apparatus according to the present invention. This allows the priority circuit, to be activated whenever, and always at the right time, the capacity of the stabilization apparatus according to the present invention is not sufficient to suppress the ship movements optimally.
According to a further embodiment of the stabilization apparatus according to the present invention, the capacity of the constant-pressure pump can be simulated, for replenishment of the reservoir, and can be taken into account in the production of the control signal, in the control device.
In order to further optimize the operation of the stabilization apparatus according to the present invention, its control device may have a control section by means of which the drive device power which may be required in order to stabilize the ship movements is adjustable. This allows certain ship movements to be accepted in order to avoid unreasonably high complexity for operation of the stabilization apparatus.
For stabilization of ship movements, stabilizers are moved from their actual position to their required position corresponding to control signals, and the control signals are produced as a function of measurement signals which correspond to the rolling movements of a ship, wherein a roll angle and a roll angle rate and/or a roll angle acceleration are detected or determined separately, and each control signal is produced from a roll angle component and a roll angle rate component and/or a roll angle acceleration component, wherein the element of the roll angle component and of the roll angle rate component and/or of the roll angle acceleration component can be preset as required in the control signal.
In the situation where the drive power available for movement of the stabilizers is insufficient to compensate not only for the roll angle but also for the roll angle rate and for the roll angle acceleration, the compensation for the roll angle, is first reduced then the compensation for the roll angle rate reduced, and then the compensation for the roll angle acceleration reduced.
The reduction in the compensation for the roll angle rate and the roll angle acceleration is introduced before the compensation for the roll angle and for the roll angle rate has been reduced completely.
Furthermore, according to the present invention it is possible for the control signals also to be produced as a function of measurement signals which correspond to pitching movements of the ship, in which a pitch angle and/or a pitch angle rate and/or a pitch angle acceleration are detected and determined separately; each control signal is produced with a signal part, which takes account of the pitching movement of the ship, from a pitch angle component and/or a pitch angle rate component and/or a pitch angle acceleration component, wherein the element of the pitch angle component and/or of the pitch angle rate component and/or of the pitch angle acceleration component can be preset as required on that signal part of the control signal which takes account of the pitching movement of the ship.
In the situation where the drive power available for movement of the stabilizers is insufficient to compensate not only for the pitch angle but also for the pitch angle rate and for the pitch angle acceleration, the compensation for the pitch angle is first reduced, and then the compensation for the pitch angle rate is reduced, and then the compensation for the pitch angle acceleration is reduced.
The reduction in the compensation for the pitch angle rate and the pitch angle acceleration is introduced before the compensation for the pitch angle and for the pitch angle rate has been reduced completely.
In the situation where the drive power available for movement of the stabilizers is insufficient to compensate for the rolling movement and/or the pitching movement of the ship, the compensation for the pitching movement is first reduced.
The reduction in the compensation for the rolling movement can be introduced before the compensation for the pitching movement has been reduced completely.
Furthermore, the control signals may be varied as a function of the ship speed.
The control signals can be attenuated as the speed increases.
The power which may be required to move the stabilizers can be varied as a function of any required or desired compensation for the ship movements.